From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
alex_gagniuc@dellteam.com, austin_bolen@dell.com,
shyam_iyer@dell.com, Keith Busch <keith.busch@intel.com>,
linux-pci@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] PCI: Check for PCIe downtraining conditions
Date: Tue, 5 Jun 2018 15:27:14 +0300 [thread overview]
Message-ID: <CAHp75VciAimPhuMDOzYdMP=S1OWGyOUh4dN4BqfsLVOpTnRBRQ@mail.gmail.com> (raw)
In-Reply-To: <20180604155523.14906-1-mr.nuke.me@gmail.com>
On Mon, Jun 4, 2018 at 6:55 PM, Alexandru Gagniuc <mr.nuke.me@gmail.com> wrote:
> PCIe downtraining happens when both the device and PCIe port are
> capable of a larger bus width or higher speed than negotiated.
> Downtraining might be indicative of other problems in the system, and
> identifying this from userspace is neither intuitive, nor straigh
> forward.
>
> The easiest way to detect this is with pcie_print_link_status(),
> since the bottleneck is usually the link that is downtrained. It's not
> a perfect solution, but it works extremely well in most cases.
Have you seen any of my comments?
For your convenience repeating below.
>
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> ---
>
> Changes since v2:
> - Check dev->is_virtfn flag
>
> Changes since v1:
> - Use pcie_print_link_status() instead of reimplementing logic
>
> drivers/pci/probe.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index ac91b6fd0bcd..a88ec8c25dd5 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2146,6 +2146,25 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
> return dev;
> }
>
> +static void pcie_check_upstream_link(struct pci_dev *dev)
> +{
> +
This is redundant blank line.
> + if (!pci_is_pcie(dev))
> + return;
> +
> + /* Look from the device up to avoid downstream ports with no devices. */
> + if ((pci_pcie_type(dev) != PCI_EXP_TYPE_ENDPOINT) &&
> + (pci_pcie_type(dev) != PCI_EXP_TYPE_LEG_END) &&
> + (pci_pcie_type(dev) != PCI_EXP_TYPE_UPSTREAM))
> + return;
I looked briefly at the use of these calls and perhaps it might make
sense to introduce
pci_is_pcie_type(dev, type) which unifies pci_is_pcie() + pci_pcie_type().
> +
> + /* Multi-function PCIe share the same link/status. */
> + if ((PCI_FUNC(dev->devfn) != 0) || dev->is_virtfn)
The one pair of parens is not needed.
> + return;
> +
> + pcie_print_link_status(dev);
> +}
> +
> static void pci_init_capabilities(struct pci_dev *dev)
> {
> /* Enhanced Allocation */
> @@ -2181,6 +2200,9 @@ static void pci_init_capabilities(struct pci_dev *dev)
> /* Advanced Error Reporting */
> pci_aer_init(dev);
>
> + /* Check link and detect downtrain errors */
> + pcie_check_upstream_link(dev);
> +
> if (pci_probe_reset_function(dev) == 0)
> dev->reset_fn = 1;
> }
> --
> 2.14.4
>
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2018-06-05 12:27 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-04 15:55 [PATCH v3] PCI: Check for PCIe downtraining conditions Alexandru Gagniuc
2018-06-05 12:27 ` Andy Shevchenko [this message]
2018-06-05 13:04 ` Andy Shevchenko
2018-07-16 21:17 ` Bjorn Helgaas
2018-07-16 22:28 ` Alex_Gagniuc
2018-07-18 21:53 ` Bjorn Helgaas
2018-07-19 15:46 ` Alex G.
2018-07-23 20:01 ` [PATCH v2] PCI/AER: Do not clear AER bits if we don't own AER Alexandru Gagniuc
2018-07-25 1:24 ` kbuild test robot
2018-07-23 20:03 ` [PATCH v5] PCI: Check for PCIe downtraining conditions Alexandru Gagniuc
2018-07-23 21:01 ` Jakub Kicinski
2018-07-23 21:52 ` Tal Gilboa
2018-07-23 22:14 ` Jakub Kicinski
2018-07-23 23:59 ` Alex G.
2018-07-24 13:39 ` Tal Gilboa
2018-07-30 23:26 ` Alex_Gagniuc
2018-07-31 6:40 ` Tal Gilboa
2018-07-31 15:10 ` Alex G.
2018-08-05 7:05 ` Tal Gilboa
2018-08-06 18:39 ` Alex_Gagniuc
2018-08-06 19:46 ` Bjorn Helgaas
2018-08-06 23:25 ` [PATCH v6 1/9] " Alexandru Gagniuc
2018-08-06 23:25 ` [PATCH v6 2/9] bnx2x: Do not call pcie_print_link_status() Alexandru Gagniuc
2018-08-06 23:25 ` [PATCH v6 3/9] bnxt_en: " Alexandru Gagniuc
2018-08-06 23:25 ` [PATCH v6 4/9] cxgb4: " Alexandru Gagniuc
2018-08-06 23:25 ` [PATCH v6 5/9] fm10k: " Alexandru Gagniuc
2018-08-07 17:52 ` Jeff Kirsher
2018-08-06 23:25 ` [PATCH v6 6/9] ixgbe: " Alexandru Gagniuc
2018-08-07 17:51 ` Jeff Kirsher
2018-08-06 23:25 ` [PATCH v6 7/9] net/mlx4: " Alexandru Gagniuc
2018-08-08 6:10 ` Leon Romanovsky
2018-08-06 23:25 ` [PATCH v6 8/9] net/mlx5: " Alexandru Gagniuc
2018-08-08 6:08 ` Leon Romanovsky
2018-08-08 14:23 ` Tal Gilboa
2018-08-08 15:41 ` Leon Romanovsky
2018-08-08 15:56 ` Tal Gilboa
2018-08-08 16:33 ` Alex G.
2018-08-08 17:27 ` Leon Romanovsky
2018-08-09 14:02 ` Bjorn Helgaas
2018-08-06 23:25 ` [PATCH v6 9/9] nfp: " Alexandru Gagniuc
2018-08-07 19:44 ` [PATCH v6 1/9] PCI: Check for PCIe downtraining conditions David Miller
2018-08-07 21:41 ` Bjorn Helgaas
2018-07-18 13:38 ` [PATCH v3] " Tal Gilboa
2018-07-19 15:49 ` Alex G.
2018-07-23 5:21 ` Tal Gilboa
2018-07-23 17:01 ` Alex G.
2018-07-23 21:35 ` Tal Gilboa
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